Although perovskite solar cells (PSCs) have demonstrated power conversion efficiency (PCE) as high as 26%, instability caused by the heterointerfaces has been an issue. Since the thermal expansion coefficient of perovskite is higher than that of SnO₂, in-plane tensile strain formed at the perovskite/SnO₂ interface is one of the causes of the instability of PSCs. We report here an effective methodology to regulate the strain via surface modification of the SnO₂ layer with a bifunctional molecule of phosphorylethanolamine (PEA) bearing phosphate and amine groups linked by an alkyl chain. The grazing incidence X-ray diffraction data showed that an in-plane tensile strain observed upon deposition of the perovskite film on the bare SnO₂ layer was substantially released by modifying the SnO₂ surface with PEA. The strain-less interface resulted in an increase in PCE from 22.87% to 24.35%. Moreover, the unencapsulated device stability was better for the PEA-modified SnO₂ than for the unmodified one: 93% of initial PCE after 1700 h versus 66% of initial PCE. Light-soaking stability of the device with the PEA-modified SnO₂ was superior to the one with the unmodified SnO₂.

中文翻译：

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由界面分子设计的无应变钙钛矿薄膜用于稳定的钙钛矿太阳能电池

尽管钙钛矿太阳能电池 (PSC) 的功率转换效率 (PCE) 高达 26%，但异质界面引起的不稳定一直是一个问题。由于钙钛矿的热膨胀系数高于SnO _{2 ，​​钙钛矿/SnO 2}界面处形成的面内拉伸应变是PSC不稳定的原因之一。我们在这里报告了一种有效的方法，通过使用带有通过烷基链连接的磷酸盐和胺基团的磷酸乙醇胺（PEA）双功能分子对SnO ₂层进行表面修饰来调节应变。掠入射X射线衍射数据表明，通过用PEA修饰SnO _{2表面，在裸SnO 2}层上沉积钙钛矿膜时观察到的面内拉伸应变基本上被释放。无应变界面导致 PCE 从 22.87% 增加到 24.35%。此外，PEA 改性 SnO ₂的未封装器件稳定性优于未改性器件：1700 小时后初始 PCE 为 93%，而初始 PCE 为 66%。具有PEA改性SnO ₂的器件的光浸泡稳定性优于具有未改性SnO ₂的器件。